London has been battered by 50mph winds that have felled trees and caused travel chaos. Powerful gusts swept across the capital as the Met Office issued a yellow "be aware" weather alert for most of the country.

Prince Philip today gave some forthright advice about the global financial collapse to Bank of England staff: "Don't do it again!"

The Duke of Edinburgh, 91, was accompanying the Queen on a visit to the bank when she was given an unexpected presentation on how it had failed to spot the crisis.

Bank expert Sujit Kapadia told her they had decided to answer the question the Queen posed at the heart of the credit crunch in 2008 when she asked academics: “Why did nobody notice it?”

As the royal couple filed out after the briefing, Philip asked "There's not another one coming, is there?" before adding: "Don't do it again."

The Queen and Philip were given a tour of the bank by Governor Sir Mervyn King that took in gold vaults stacked with £27 billion of bars of the precious metal.

They each signed an unissued £1 million note, with Philip picking his up and asking: "Is this just lying about? You won't miss it, will you?"

The Queen reportedly saw her fortune fall in value by 25 per cent as a result of the crash.

After she first posed the question about what caused the global collapse, the British Academy convened a round-table of experts, who then wrote to the Queen apologising for failing to predict the financial crisis.

Changes introduced by the Government will see the Bank of England get regulatory powers over the financial system.

Philip appeared to question what its legions of staff did when he spotted hundreds lined up for the royal visit. He asked two women: "Do you work here?... On occasion?"

The signing of a banknote to record a VIP visit is a tradition that dates back to the early part of the 19th century.

However, in a sign of how inflation has eroded values, a £1,000 note was replaced with a £1 million note in 1994.

The notes signed by the Queen and Philip were placed in the bank’s distinguished visitors book.

Today’s visit was the Queen's ninth to the bank but first since 1998.

In 2009 Sir Mervyn became the first bank governor to be invited to Buckingham Palace for private talks. He retires next June and will be replaced by Mark Carney, currently governor of the Canadian central bank.

The Queen, as Princess Elizabeth, first visited the bank, in Threadneedle Street, in November 1937 when she accompanied Queen Mary.

The Queen’s portrait first appeared on a banknote in 1960 - the first time an image of the monarch bad been used. Five different portraits have been used during her reign - by Robert Austin (1960), Reynolds Stone (1963), Harry Ecclestone (1970 and 1971) and Roger Withington (1990).